Field of the Invention
The present invention relates to, in particular, an image processing apparatus, an image processing method, and a program that are suitably used for filter processing.
Description of the Related Art
Generally, in image-capturing using compact digital cameras, a relatively broad distance range comes into focus as compared with a case of image-capturing using single-lens reflection cameras. Thus, it is difficult for compact digital cameras to capture an image in which a background is largely blurred as in the case of single-lens reflection cameras. Therefore, to obtain a large blurring effect, conventional compact digital cameras perform digital filter processing so as to add blurring that has the size equivalent to the size of blurring obtainable through image-capturing using single-lens reflection cameras to a captured image.
For example, Japanese Patent Application Laid-Open No. 2004-102904 discloses a technique of applying small-sized filter processing on a reduced image and then enlarging the image to an original size so as to add large blurring to an image through small-sized filter processing. In addition, Japanese Patent Application Laid-Open No. 2004-145615 discloses a technique of dividing a large-sized filter into small-sized filters, and adding small-sized filtering results, thereby obtaining a result equivalent to that obtainable in filtering using a large-sized filter, while reducing the circuit size.
The conventional art disclosed in Japanese Patent Application Laid-Open No. 2004-102904, however, cannot faithfully reproduce background blurring as in the case of single-lens reflection cameras due to the small filtering size. For example, as one imaging technique of single-lens reflection cameras, there is a method of largely and roundly blurring a point light source in a background. Nevertheless, details of the shape of the round blurring cannot be sufficiently expressed through the small-sized filter processing disclosed in Japanese Patent Application Laid-Open No. 2004-102904 described above. In addition, the method described in Japanese Patent Application Laid-Open No. 2004-145615 has such an issue that the calculation amount required for the filter processing increases.